Free Excretion MCQs with Answers

• A. ammonia
• B. urea
• C. uric acid
• D. creatine

Explanation: Surplus amino acids are deaminated in the liver and the toxic ammonia produced is converted at once into far less toxic urea by the…

• A. uric acid is more toxic and so must be removed faster
• B. they have no liver in which to make urea
• C. uric acid is almost insoluble and can be excreted as a paste, saving water
• D. uric acid contains no nitrogen

Explanation: Being nearly insoluble, uric acid can be voided as a semi solid with very little water, which suits animals that must conserve water and…

• A. the dialysis fluid contains enzymes that destroy urea
• B. the blood is heated so that urea evaporates
• C. urea is actively pumped across the membrane
• D. the dialysis fluid contains no urea, so urea diffuses out across a partially permeable membrane

Explanation: Dialysis fluid is made with the same concentrations of glucose and mineral ions as normal blood plasma but with no urea at all, so only…

• A. The passing of undigested cellulose in faeces
• B. The loss of dead cells from the surface of the skin
• C. The removal of hair when it is cut
• D. The removal of carbon dioxide by the lungs

Explanation: Excretion is the removal of the waste products of the body's own metabolism, and carbon dioxide is made by respiration inside every cell…

• A. Water excretion
• B. Sodium reabsorption
• C. Potassium reabsorption
• D. Glucose excretion

Explanation: Aldosterone increases Na+ reabsorption and K+ secretion in the distal tubule and collecting duct.

• A. Freshwater Fish
• B. Amphibians
• C. Birds
• D. Mammals

Explanation: Uric acid is almost insoluble, so it can be excreted as a paste with very little water, which suits birds both for flight and for…

• A. Skin
• B. Liver
• C. Lungs
• D. GIT

Explanation: Sweat is produced by sweat glands and sebum by sebaceous glands, both located in the skin.

• A. hepatology
• B. hematology
• C. mycology
• D. None of These

Explanation: Hepatology is the branch of medicine concerned with the liver and its diseases.

• A. Excretion
• B. Circulation
• C. Reproduction
• D. Pollution

Explanation: Excretion removes metabolic wastes such as urea and also eliminates excess water and salts from the body, mainly through the kidneys.

• A. Kidney
• B. Liver
• C. Lungs
• D. Heart

Explanation: The liver is a major metabolic organ, carrying out carbohydrate, lipid, and protein metabolism as well as detoxification and synthesis of…

• A. External space
• B. Internal Body cavity
• C. In gut
• D. In Bladder

Explanation: In an earthworm, the nephrostome is the ciliated funnel that opens internally into the coelom and receives coelomic fluid.

• A. Nephrostome
• B. Nephridiopore
• C. Flame cell
• D. Anus

Explanation: The nephrostome is the funnel-shaped opening through which an earthworm's nephridium receives fluid from the coelom.

• A. Blood
• B. Lymph
• C. Gut
• D. Hemolymph

Explanation: In insects, Malpighian tubules remove nitrogenous wastes and salts from the haemolymph, the insect equivalent of blood.

• A. Nephrostome
• B. Nephridiopore
• C. Both of these
• D. None of these

Explanation: The nephrostome of an earthworm has cilia that create a current and draw coelomic fluid into the nephridium.

• A. Hydra
• B. Planaria.
• C. Humans
• D. Birds.

Explanation: Birds excrete nitrogen mainly as uric acid, which requires little water and forms a semi-solid paste, an adaptation useful for flight and…

• A. Ammonia
• B. Urea
• C. Uric acid
• D. Trimethylamine oxide

Explanation: Ammonia is the most toxic of these nitrogenous wastes because it interferes rapidly with cellular metabolism and must be diluted with…

• A. Round worms
• B. Flateworm
• C. Tape worms
• D. Segmented worms

Explanation: Protonephridia are flame-cell excretory systems found in flatworms, including planarians and tapeworms.

• A. Ammonia
• B. Urea
• C. Uric acid
• D. Trimethylamine oxide

Explanation: Aquatic animals commonly excrete ammonia because it is highly toxic but can be rapidly diluted and removed in abundant water.

• A. Excessive urea which will increase their internal solute concentration and prevent body shrinkage in hypertonic environment
• B. Trimethyl alanine
• C. Ammonia
• D. Trimethylamine oxide

Explanation: Trimethylamine oxide, commonly called TMAO, acts as an important osmolyte in marine animals and helps maintain internal solute balance in…

• A. Bony Marine fishes
• B. Fresh water fishes
• C. Both depending upon the surrounding water
• D. None of these

Explanation: Freshwater fishes gain water by osmosis because their body fluids are more concentrated than the surrounding water, so they excrete a…